Different behavior when declaration type is different(Set vs TreeSet)

Question

    var set = TreeSet(5,4,3,2,1)
    println(set)

    val diffSet: TreeSet[Int] = set
    // if I change above code to val diffSet: Set[Int] = set
    // the result is          


        

Answer 1

Change the sig of genSet to return a SortedSet

def genSet:SortedSet[Int] = {
  TreeSet(5, 4, 3, 2, 1)
}

This is probably some sort of bug. I would have expected your code to work too.

I think map is the culprit. This results in the same behavior:

for (i <- genSet.map(_ + 1)) { println(i) }

And for(i <- genSet; x = i + 1) equates to for(x <- genSet.map({i => i + 1}))